Assesment of Periodical Nitrogen Use of Tomato Using a Computer Program

Abstract

In this study, conducted with lysimeters, we wanted to test the performance of LEACHN computer model to simulate the nitrogen uptake of plants at experimental sites. Nitrogen fertilizer at the rates of 0, 80, 160 and 240 kg N.ha⁻¹ was side dressed in two split applications, first half as ammonium sulphate and the other half as ammonium nitrate. The lysimeters were irrigated based on program C 1.00, C referring to class A-Pan evaporation coefficients. Yield and N-use efficiency increased with increasing nitrogen rates up to 160 kg N.ha ⁻¹, however, they decreased drastically under 240 kg N.ha ⁻¹. The results also releaved that some fruit qualities were significantly affected by N-rates. The ability of LEACHN model to simulate crop-N-use was tested using Model parameters for experimental site. Significant correlations (r = 0.95 for 1996 and r = 0.94 for 1997) were found between measured and simulated values for the plant N-uptake, suggesting that the LEACHN model can be confidently used to estimate the crop-N consumption.